The purpose of this study is to evaluate the safety and efficacy of 3 doses of oral lobucavir (100mg twice daily, 200mg daily, and 200mg twice daily) in the treatment of genital herpes. In this Phase II, multicenter, randomized, double-blind, placebo controlled clinical trial 2860 subjects will be enrolled at 60-100 clinical centers. All subjects will receive 5 days of treatment with either lobucavir or matching placebo. Treatment will be followed by a 30-day post-treatment follow up period.